CRISPR has revolutionized the world of gene editing, but now an even more powerful system, called “bridge editing,” may offer the ability to completely reshape the genome. This new system has been developed by Patrick Hsu and his team at the Arc Institute in California. The system is based on physically linking or “bridging” two pieces of DNA, allowing for the modification of large sections of the genome.
Since its debut in 2012, CRISPR gene editing has transformed biology. The CRISPR-Cas9 system is being used for a wide range of applications, and last year, it received approval for its first medical treatments. However, the original form of CRISPR, which uses the Cas9 protein, is primarily destructive — it cuts genes rather than edits them in a precise way.
CRISPR-Cas9 works with two components: one part is a guide RNA molecule that searches for a specific segment of DNA, and the other part is a protein that cuts the DNA. Once the DNA is cut, the cell attempts to repair it. This repair process often introduces errors, which lead to targeted mutations at the cut site.
Bridge editing differs in a significant way. In this system, a recombinase protein is linked to the guide RNA. The system is programmed to search for two separate DNA sequences, not just one. It can be used to join, delete, or invert DNA sequences of any length. While similar technologies have existed before, they usually required multiple steps and often left behind “scars” — unwanted genetic remnants. Bridge editing is “scarless” and offers unprecedented control over genome modification.
So far, bridge editing has only been successfully demonstrated in bacterial cells or test tubes. How it will perform in human cells remains to be seen. However, experts believe that even if the system faces challenges in early trials, it can be adapted over time to work in human cells as well.
Bridge editing represents a major step forward that could open new possibilities in genome modification. It may not only be used to replace faulty genes but also to completely redesign the genomes of plants and animals. With this new technology, we are moving toward a broader vision of genome design, potentially ushering in a new revolution in the field of biology.